- Highly Active Cooperative Lewis Acid—Ammonium Salt Catalyst for the Enantioselective Hydroboration of Ketones
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Enantiopure secondary alcohols are fundamental high-value synthetic building blocks. One of the most attractive ways to get access to this compound class is the catalytic hydroboration. We describe a new concept for this reaction type that allowed for exceptional catalytic turnover numbers (up to 15 400), which were increased by around 1.5–3 orders of magnitude compared to the most active catalysts previously reported. In our concept an aprotic ammonium halide moiety cooperates with an oxophilic Lewis acid within the same catalyst molecule. Control experiments reveal that both catalytic centers are essential for the observed activity. Kinetic, spectroscopic and computational studies show that the hydride transfer is rate limiting and proceeds via a concerted mechanism, in which hydride at Boron is continuously displaced by iodide, reminiscent to an SN2 reaction. The catalyst, which is accessible in high yields in few steps, was found to be stable during catalysis, readily recyclable and could be reused 10 times still efficiently working.
- Titze, Marvin,Heitk?mper, Juliane,Junge, Thorsten,K?stner, Johannes,Peters, René
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supporting information
p. 5544 - 5553
(2021/02/05)
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- Novel non-metal catalyst for catalyzing asymmetric hydrogenation of ketone and alpha, beta-unsaturated ketone
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The invention discloses a novel non-metal catalyst for catalyzing asymmetric hydrogenation of ketone and alpha, beta-unsaturated ketone. The preparation method of a chiral alcohol compound shown as formula IV comprises the following step of: reacting a ketone compound shown as formula V with hydrogen under the catalysis of tri(4-hydrotetrafluorophenyl)boron and a chiral oxazoline compound to obtain the chiral alcohol compound shown as the formula IV; the preparation method of a chiral tetralone compound shown as formula VI comprises the following step of: under the catalysis of tri(4-hydrotetrafluorophenyl)boron and a chiral oxazoline compound, reacting an alpha, beta-unsaturated ketone compound shown as formula VII with hydrogen to obtain the chiral tetralone compound shown as the formula VI. The method has the advantages of easy synthesis of raw materials, mild reaction conditions, simple operation, high stereoselectivity and the like, the ee value of the product is up to 92%, and the yield is up to 99%.
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Paragraph 0168-0173
(2021/04/26)
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- Enantioselective direct, base-free hydrogenation of ketones by a manganese amido complex of a homochiral, unsymmetrical P-N-P′ ligand
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The use of manganese in homogeneous hydrogenation catalysis has been a recent focus in the pursuit of more environmentally benign base metal catalysts. It has great promise with its unique reactivity when coupled with metal-ligand cooperation of aminophosphine pincer ligands. Here, a manganese precatalyst Mn(P-N-P′)(CO)2, where P-N-P′ is the amido form of the ligand (S,S)-PPh2CHPhCHPhNHCH2CH2PiPr2, has been synthesized and used for base-free ketone hydrogenation. This catalyst shows exceptionally high enantioselectivity and good activity, with tolerance for base-sensitive substrates. NMR structural analysis of intermediates formed by the reaction of the amido complex with hydrogen under pressure identified a reactive hydride with an NOE contact with the syn amine proton. Computational analysis of the catalytic cycle reveals that the heterolytic splitting of dihydrogen across the MnN bond in the amido complex has a low barrier while the hydride transfer to the ketone is the turnover-limiting step. The pro-S transition state is found to be usually much lower in energy than the pro-R transition state depending on the ketone structure, consistent with the high (S) enantiomeric excess in the alcohol products. The energy to reach the transition state is higher for the distortion of the in-coming ketone than that of the hydride complex. In a one-to-one comparison with the similar iron catalyst FeH2(CO)(P-NH-P′), the manganese catalyst is found to have higher enantioselectivity, often over 95% ee, while the iron catalyst has higher activity and productivity. An explanation of these differences is provided on the basis of the more deformable iron hydride complex due to the smaller hydride ligands.
- Seo, Chris S. G.,Tsui, Brian T. H.,Gradiski, Matthew V.,Smith, Samantha A. M.,Morris, Robert H.
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p. 3153 - 3163
(2021/05/25)
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- Ambient-pressure highly active hydrogenation of ketones and aldehydes catalyzed by a metal-ligand bifunctional iridium catalyst under base-free conditions in water
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A green, efficient, and high active catalytic system for the hydrogenation of ketones and aldehydes to produce corresponding alcohols under atmospheric-pressure H2 gas and ambient temperature conditions was developed by a water-soluble metal–ligand bifunctional catalyst [Cp*Ir(2,2′-bpyO)(OH)][Na] in water without addition of a base. The catalyst exhibited high activity for the hydrogenation of ketones and aldehydes. Furthermore, it was worth noting that many readily reducible or labile functional groups in the same molecule, such as cyan, nitro, and ester groups, remained unchanged. Interestingly, the unsaturated aldehydes can be also selectively hydrogenated to give corresponding unsaturated alcohols with remaining C=C bond in good yields. In addition, this reaction could be extended to gram levels and has a large potential of wide application in future industrial.
- Wang, Rongzhou,Yue, Yuancheng,Qi, Jipeng,Liu, Shiyuan,Song, Ao,Zhuo, Shuping,Xing, Ling-Bao
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- Method for synthesizing secondary alcohol in water phase
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The invention discloses a method for synthesizing secondary alcohol in a water phase. The method comprises the following steps: taking ketone as a raw material, selecting water as a solvent, and carrying out catalytic hydrogenation reaction on the ketone in the presence of a water-soluble catalyst to obtain the secondary alcohol, wherein the catalyst is a metal iridium complex [Cp * Ir (2, 2'-bpyO)(OH)][Na]. Water is used as the solvent, so that the use of an organic solvent is avoided, and the method is more environment-friendly; the reaction is carried out at relatively low temperature and normal pressure, and the reaction conditions are mild; alkali is not needed in the reaction, so that generation of byproducts is avoided; and the conversion rate of the raw materials is high, and the yield of the obtained product is high. The method not only has academic research value, but also has a certain industrialization prospect.
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Paragraph 0032-0033
(2021/07/14)
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- Ni2P Nanoalloy as an Air-Stable and Versatile Hydrogenation Catalyst in Water: P-Alloying Strategy for Designing Smart Catalysts
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Non-noble metal-based hydrogenation catalysts have limited practical applications because they exhibit low activity, require harsh reaction conditions, and are unstable in air. To overcome these limitations, herein we propose the alloying of non-noble metal nanoparticles with phosphorus as a promising strategy for developing smart catalysts that exhibit both excellent activity and air stability. We synthesized a novel nickel phosphide nanoalloy (nano-Ni2P) with coordinatively unsaturated Ni active sites. Unlike conventional air-unstable non-noble metal catalysts, nano-Ni2P retained its metallic nature in air, and exhibited a high activity for the hydrogenation of various substrates with polar functional groups, such as aldehydes, ketones, nitriles, and nitroarenes to the desired products in excellent yields in water. Furthermore, the used nano-Ni2P catalyst was easy to handle in air and could be reused without pretreatment, providing a simple and clean catalyst system for general hydrogenation reactions.
- Fujita, Shu,Yamaguchi, Sho,Yamasaki, Jun,Nakajima, Kiyotaka,Yamazoe, Seiji,Mizugaki, Tomoo,Mitsudome, Takato
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supporting information
p. 4439 - 4446
(2021/02/09)
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- KB3H8: An environment-friendly reagent for the selective reduction of aldehydes and ketones to alcohols
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Selective reduction of aldehydes and ketones to their corresponding alcohols with KB3H8, an air- and moisture-stable, nontoxic, and easy-to-handle reagent, in water and THF has been explored under an air atmosphere for the first time. Control experiments illustrated the good selectivity of KB3H8 over NaBH4 for the reduction of 4-acetylbenzaldehyde and aromatic keto esters. This journal is
- Li, Xinying,Mi, Tongge,Guo, Wenjing,Ruan, Zhongrui,Guo, Yu,Ma, Yan-Na,Chen, Xuenian
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supporting information
p. 12776 - 12779
(2021/12/10)
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- Four-Coordinated Manganese(II) Disilyl Complexes for the Hydrosilylation of Aldehydes and Ketones with 1,1,3,3-Tetramethyldisiloxane
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The coordinatively unsaturated manganase(II) bis(supersilyl) complex Mn[Si(SiMe3)3]2(THF)2 (2) was synthesized in one step via the reaction of MnBr2 with two equivalents of KSi(SiMe3)3 in THF. Complex 2 acts as an effective precatalyst for the catalytic hydrosilylation of aldehydes and ketones with 1,1,3,3-tetramethyldisiloxane (TMDS). The catalytic efficiency can be improved by combining 2 and adamantyl isocyanide (CNAd). The stoichiometric reaction of 2 and two equivalents of CNAd led to the isolation of Mn[Si(SiMe3)3]2(CNAd)2 (3) in high yield. Complex 3 shows superior catalytic performance than 2 in the hydrosilylation of relatively unreactive ketones.
- Saito, Kyoka,Ito, Tatsuyoshi,Arata, Shogo,Sunada, Yusuke
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p. 1152 - 1156
(2020/12/18)
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- Reaction of Diisobutylaluminum Borohydride, a Binary Hydride, with Selected Organic Compounds Containing Representative Functional Groups
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The binary hydride, diisobutylaluminum borohydride [(iBu)2AlBH4], synthesized from diisobutylaluminum hydride (DIBAL) and borane dimethyl sulfide (BMS) has shown great potential in reducing a variety of organic functional groups. This unique binary hydride, (iBu)2AlBH4, is readily synthesized, versatile, and simple to use. Aldehydes, ketones, esters, and epoxides are reduced very fast to the corresponding alcohols in essentially quantitative yields. This binary hydride can reduce tertiary amides rapidly to the corresponding amines at 25 °C in an efficient manner. Furthermore, nitriles are converted into the corresponding amines in essentially quantitative yields. These reactions occur under ambient conditions and are completed in an hour or less. The reduction products are isolated through a simple acid-base extraction and without the use of column chromatography. Further investigation showed that (iBu)2AlBH4 has the potential to be a selective hydride donor as shown through a series of competitive reactions. Similarities and differences between (iBu)2AlBH4, DIBAL, and BMS are discussed.
- Amberchan, Gabriella,Snelling, Rachel A.,Moya, Enrique,Landi, Madison,Lutz, Kyle,Gatihi, Roxanne,Singaram, Bakthan
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supporting information
p. 6207 - 6227
(2021/05/06)
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- Uranyl(VI) Triflate as Catalyst for the Meerwein-Ponndorf-Verley Reaction
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Catalytic transformation of oxygenated compounds is challenging in f-element chemistry due to the high oxophilicity of the f-block metals. We report here the first Meerwein-Ponndorf-Verley (MPV) reduction of carbonyl substrates with uranium-based catalysts, in particular from a series of uranyl(VI) compounds where [UO2(OTf)2] (1) displays the greatest efficiency (OTf = trifluoromethanesulfonate). [UO2(OTf)2] reduces a series of aromatic and aliphatic aldehydes and ketones into their corresponding alcohols with moderate to excellent yields, using iPrOH as a solvent and a reductant. The reaction proceeds under mild conditions (80 °C) with an optimized catalytic charge of 2.3 mol % and KOiPr as a cocatalyst. The reduction of aldehydes (1-10 h) is faster than that of ketones (>15 h). NMR investigations clearly evidence the formation of hemiacetal intermediates with aldehydes, while they are not formed with ketones.
- Kobylarski, Marie,Monsigny, Louis,Thuéry, Pierre,Berthet, Jean-Claude,Cantat, Thibault
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supporting information
p. 16140 - 16148
(2021/11/01)
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- Asymmetric Hydrogenation of Ketones and Enones with Chiral Lewis Base Derived Frustrated Lewis Pairs
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The concept of frustrated Lewis pairs (FLPs) has been widely applied in various research areas, and metal-free hydrogenation undoubtedly belongs to the most significant and successful ones. In the past decade, great efforts have been devoted to the synthesis of chiral boron Lewis acids. In a sharp contrast, chiral Lewis base derived FLPs have rarely been disclosed for the asymmetric hydrogenation. In this work, a novel type of chiral FLP was developed by simple combination of chiral oxazoline Lewis bases with achiral boron Lewis acids, thus providing a promising new direction for the development of chiral FLPs in the future. These chiral FLPs proved to be highly effective for the asymmetric hydrogenation of ketones, enones, and chromones, giving the corresponding products in high yields with up to 95 % ee. Mechanistic studies suggest that the hydrogen transfer to simple ketones likely proceeds in a concerted manner.
- Du, Haifeng,Feng, Xiangqing,Gao, Bochao,Meng, Wei
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supporting information
p. 4498 - 4504
(2020/02/05)
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- Enantioselective Hydroboration of Ketones Catalyzed by Rare-Earth Metal Complexes Containing Trost Ligands
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Four chiral dinuclear rare-earth metal complexes [REL1]2 (RE = Y(1), Eu(2), Nd(3), La (4)) stabilized by Trost proligand H3L1 (H3L1 = (S,S)-2,6-bis[2-(hydroxydiphenylmethyl)pyrrolidin-1-ylmethyl]-4-methylphenol) were first prepared, and all were characterized by X-ray diffraction. Complex 4 was employed as the catalyst for enantioselective hydroboration reaction of substituted ketones, and the corresponding secondary alcohols with excellent yields and high ee values were obtained using reductant HBpin. The same result was also achieved using the combination of lanthanium amides La[N(SiMe3)2]3 with Trost proligand H3L1 in a 1:1 molar ratio. The experimental findings and DFT calculation revealed the possible mechanism of the enantioselective hydroboration reaction and defined the origin of the enantioselectivity in the current system.
- Lu, Chengrong,Sun, Yuli,Xue, Mingqiang,Zhao, Bei
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p. 10504 - 10513
(2020/09/23)
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- Zinc Hydride-Catalyzed Hydrofuntionalization of Ketones
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Three new dimeric bis-guanidinate zinc(II) alkyl, halide, and hydride complexes [LZnEt]2 (1), [LZnI]2 (2) and [LZnH]2 (3) were prepared. Compound 3 was successfully employed for the hydrosilylation and hydroboration of a vast number of ketones. The catalytic performance of 3 in the hydroboration of acetophenone exhibits a turnover frequency, reaching up to 5800 h-1, outperforming that of reported zinc hydride catalysts. Notably, both intra- and intermolecular chemoselective hydrosilylation and hydroboration reactions have been investigated.
- Sahoo, Rajata Kumar,Mahato, Mamata,Jana, Achintya,Nembenna, Sharanappa
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p. 11200 - 11210
(2020/10/12)
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- Lithium Bromide/HBpin: A Mild and Effective Catalytic System for the Selective Hydroboration of Aldehydes and Ketones
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The catalytic hydroboration of aldehydes and ketones with HBpin was examined using simple and commercially available metal salts (Li, Na, and K). Among the tested salts, LiBr (0.5–1.0 mol%) was found to be an efficient catalyst for the hydroboration of various aldehydes and ketones at room temperature. Further, the chemoselective hydroboration of aldehydes over ketones was also demonstrated.
- An, Duk Keun,Choi, Hyeon Seong,Hwang, Hyonseok,Kim, Hanbi,Lee, Ji Hye,Shin, Hye Lim,Yi, Jaeeun
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p. 1009 - 1018
(2020/10/12)
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- Low-valence anionic α-diimine iron complexes: Synthesis, characterization, and catalytic hydroboration studies
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The synthesis of rare anionic heteroleptic and homoleptic α-diimine iron complexes is described. Heteroleptic BIAN (bis(aryl)iminoacenaphthene) complexes 1-[K([18]c-6)-(thf)0.5] and 2-[K([18]c-6)(thf)2] were synthesized by reduction of the [(BIAN)FeBr2] precursor complex using stoichiometric amounts of potassium graphite in the presence of the corresponding olefin. The electronic structure of these paramagnetic species was investigated by numerous spectroscopic analyses (NMR, EPR, 57Fe M?ssbauer, UV-vis), magnetic measurements (Evans NMR method, SQUID), and theoretical techniques (DFT, CASSCF). Whereas anion 1 is a low-spin complex, anion 2 consists of an intermediate-spin Fe(III) center. Both complexes are efficient precatalysts for the hydroboration of carbonyl compounds under mild reaction conditions. The reaction of bis(anthracene) ferrate(1-) gave the homoleptic BIAN complex 3-[K([18]c-6)(thf)], which is less catalytically active. The electronic structure was elucidated with the same techniques as described for complexes 1-[K([18]c-6)(thf)0.5] and 2-[K([18]c-6)(thf)2] and revealed an Fe(II) species in a quartet ground state.
- Bodensteiner, Michael,Coburger, Peter,Demeshko, Serhiy,Gawron, Martin,Maier, Thomas M.,Meyer, Franc,Wolf, Robert,de Bruin, Bas,van Leest, Nicolaas P.
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p. 16035 - 16052
(2020/11/20)
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- Investigation into an Unexpected Impurity: A Practical Approach to Process Development for the Addition of Grignard Reagents to Aldehydes Using Continuous Flow Synthesis
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This work presents a case study of process development using continuous flow synthesis. In developing a process for manufacturing drug substances in batch reactors, we unexpectedly obtained a significant amount of a trimerized byproduct on addition of MeMgBr to an aldehyde. Consideration of a plausible generation mechanism for the byproduct indicated that it arose from a reaction between the starting material and the Mg salt of the target product. This led us to try applying continuous flow synthesis to the process to shorten the time during which the starting material coexists with the Mg salt of the target product. This led to drastic suppression of the byproduct under very mild conditions and the establishment of a more robust process than that for batch reactors.
- Hosoya, Masahiro,Kurose, Noriyuki,Nishijima, Shogo
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- Continuous-Flow Amide and Ester Reductions Using Neat Borane Dimethylsulfide Complex
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Reductions of amides and esters are of critical importance in synthetic chemistry, and there are numerous protocols for executing these transformations employing traditional batch conditions. Notably, strategies based on flow chemistry, especially for amide reductions, are much less explored. Herein, a simple process was developed in which neat borane dimethylsulfide complex (BH3?DMS) was used to reduce various esters and amides under continuous-flow conditions. Taking advantage of the solvent-free nature of the commercially available borane reagent, high substrate concentrations were realized, allowing outstanding productivity and a significant reduction in E-factors. In addition, with carefully optimized short residence times, the corresponding alcohols and amines were obtained in high selectivity and high yields. The synthetic utility of the inexpensive and easily implemented flow protocol was further corroborated by multigram-scale syntheses of pharmaceutically relevant products. Owing to its beneficial features, including low solvent and reducing agent consumption, high selectivity, simplicity, and inherent scalability, the present process demonstrates fewer environmental concerns than most typical batch reductions using metal hydrides as reducing agents.
- ?tv?s, Sándor B.,Kappe, C. Oliver
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p. 1800 - 1807
(2020/02/27)
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- Efficient Transfer Hydrogenation of Ketones using Methanol as Liquid Organic Hydrogen Carrier
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Herein, we demonstrate an efficient protocol for transfer hydrogenation of ketones using methanol as practical and useful liquid organic hydrogen carrier (LOHC) under Ir(III) catalysis. Various ketones, including electron-rich/electron-poor aromatic ketones, heteroaromatic and aliphatic ketones, have been efficiently reduced into their corresponding alcohols. Chemoselective reduction of ketones was established in the presence of various other reducible functional groups under mild conditions.
- Garg, Nidhi,Paira, Soumen,Sundararaju, Basker
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p. 3472 - 3476
(2020/05/29)
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- Transfer Hydrogenation of Ketones and Imines with Methanol under Base-Free Conditions Catalyzed by an Anionic Metal-Ligand Bifunctional Iridium Catalyst
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An anionic iridium complex [Cp*Ir(2,2′-bpyO)(OH)][Na] was found to be a general and highly efficient catalyst for transfer hydrogenation of ketones and imines with methanol under base-free conditions. Readily reducible or labile substituents, such as nitro, cyano, and ester groups, were tolerated under present reaction conditions. Notably, this study exhibits the unique potential of anionic metal-ligand bifunctional iridium catalysts for transfer hydrogenation with methanol as a hydrogen source.
- Han, Xingyou,Li, Feng,Liu, Peng,Wang, Rongzhou,Xu, Jing
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p. 2242 - 2249
(2020/03/13)
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- Borohydride intermediates pave the way for magnesium-catalysed enantioselective ketone reduction
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A magnesium precatalyst for the highly enantioselective hydro-boration of CO bonds is reported. The mechanistic basis of the unprecedented selectivity of this transformation has been investi-gated experimentally by isolation of catalytic intermediates and theoretically by DFT calculations. The facile formation of a magnesium borohydride species is critical in overcoming competing pathways in the selectivity-determining insertion step.
- Vasilenko, Vladislav,Blasius, Clemens K.,Wadepohl, Hubert,Gade, Lutz H.
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supporting information
p. 1203 - 1206
(2020/02/04)
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- N-Heterocyclic Carbene (NHC)-Stabilized Ru0 Nanoparticles: In Situ Generation of an Efficient Transfer Hydrogenation Catalyst
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Tethered and untethered ruthenium half-sandwich complexes were synthesized and characterized spectroscopically. X-ray crystallographic analysis of three untethered and two tethered Ru N-heterocyclic carbene (NHC) complexes were also carried out. These RuNHC complexes catalyze transfer hydrogenation of aromatic ketones in 2-propanol under reflux, optimally in the presence of (25 mol %) KOH. Under these conditions, the formation of 2–3 nm-sized Ru0 nanoparticles was detected by TEM measurements. A solid-state NMR investigation of the nanoparticles suggested that the NHC ligands were bound to the surface of the Ru nanoparticles (NPs). This base-promoted route to NHC-stabilized ruthenium nanoparticles directly from arene-tethered ruthenium–NHC complexes and from untethered ruthenium–NHC complexes is more convenient than previously known routes to NHC-stabilized Ru nanocatalysts. Similar catalytically active RuNPs were also generated from the reaction of a mixture of [RuCl2(p-cymene)]2 and the NHC precursor with KOH in isopropanol under reflux. The transfer hydrogenation catalyzed by these NHC-stabilized RuNPs possess a high turnover number. The catalytic efficiency was significantly reduced if nanoparticles were exposed to air or allowed to aggregate and precipitate by cooling the reaction mixtures during the reaction.
- Kathuria, Lakshay,Din Reshi, Noor U.,Samuelson, Ashoka G.
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supporting information
p. 7622 - 7630
(2020/05/29)
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- Asymmetric Magnesium-Catalyzed Hydroboration by Metal-Ligand Cooperative Catalysis
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Asymmetric catalysis with readily available, cheap, and non-toxic alkaline earth metal catalysts represents a sustainable alternative to conventional synthesis methodologies. In this context, we describe the development of a first MgII-catalyzed enantioselective hydroboration providing the products with excellent yields and enantioselectivities. NMR spectroscopy studies and DFT calculations provide insights into the reaction mechanism and the origin of the enantioselectivity which can be explained by a metal-ligand cooperative catalysis pathway involving a non-innocent ligand.
- Falconnet, Alban,Magre, Marc,Maity, Bholanath,Cavallo, Luigi,Rueping, Magnus
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supporting information
p. 17567 - 17571
(2019/11/13)
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- An isolable iron(ii) bis(supersilyl) complex as an effective catalyst for reduction reactions
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An isolable 14-electron iron bis(supersilyl) complex, Fe[Si(SiMe3)3]2(THF)2, was successfully synthesized from the reaction of FeBr2 with K[Si(SiMe3)3] and its structure was unambiguously determined by single-crystal X-ray diffraction analysis. The complex is coordinatively unsaturated and exhibits high catalytic activity toward the hydrosilylation of carbonyl compounds and the reductive silylation of dinitrogen.
- Arata, Shogo,Sunada, Yusuke
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p. 2891 - 2895
(2019/03/06)
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- Borinic Acid Mediated Hydrosilylations: Reductions of Carbonyl Derivatives
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4-Fluoro-2-chlorophenylborinic acid acts as a precatalyst in the presence of phenylsilane for the facile reduction of ketones, aldehydes and imines. Notably, synergistic mediation of a tertiary amine was found essential to trigger silicon to boron hydride transfer to generate a key amine–diarylhydroborane Lewis complex.
- Chardon, Aurélien,Rouden, Jacques,Blanchet, Jér?me
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supporting information
p. 995 - 998
(2018/12/13)
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- Deoxygenative cross-electrophile coupling of benzyl chloroformates with aryl iodides
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This work describes Ni-catalyzed cross-electrophile coupling of benzyl chloroformate derivatives with aryl iodides that generates a wide range of diaryl methane products. The mild reaction conditions merit the C-O bond radical fragmentation of benzyl chloroformates via halide abstraction or a single electron reduction by a Ni catalyst. This work offers a new substrate type for cross-electrophile couplings.
- Pan, Yingying,Gong, Yuxin,Song, Yanhong,Tong, Weiqi,Gong, Hegui
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supporting information
p. 4230 - 4233
(2019/05/06)
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- A Practical and Stereoselective In Situ NHC-Cobalt Catalytic System for Hydrogenation of Ketones and Aldehydes
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Homogeneous catalytic hydrogenation of carbonyl groups is a synthetically useful and widely applied organic transformation. Sustainable chemistry goals require replacing conventional noble transition metal catalysts for hydrogenation by earth-abundant base metals. Herein, we report how a practical in situ catalytic system generated by easily available pincer NHC precursors, CoCl2, and a base enabled efficient and high-yielding hydrogenation of a broad range of ketones and aldehydes (over 50 examples and a maximum turnover number [TON] of 2,610). This is the first example of NHC-Co-catalyzed hydrogenation of C=O bonds using flexible pincer NHC ligands consisting of a N-H substructure. Diastereodivergent hydrogenation of substituted cyclohexanone derivatives was also realized by fine-tuning of the steric bulk of pincer NHC ligands. Additionally, a bis(NHCs)-Co complex was successfully isolated and fully characterized, and it exhibits excellent catalytic activity that equals that of the in-situ-formed catalytic system. Catalytic hydrogenation is a powerful tool for the reduction of organic compounds in both fine and bulk chemical industries. To improve sustainability, more ecofriendly, inexpensive, and earth-abundant base metals should be employed to replace the precious metals that currently dominate the development of hydrogenation catalysts. However, the majority of the base-metal catalysts that have been reported involve expensive, complex, and often air- and moisture-sensitive phosphine ligands, impeding their widespread application. From a mixture of the stable CoCl2, imidazole salts, and a base, our newly developed catalytic system that formed easily in situ enables efficient and stereoselective hydrogenation of C=O bonds. We anticipate that this easily accessible catalytic system will create opportunities for the design of practical base-metal hydrogenation catalysts. A practical in situ catalytic system generated by a mixture of easily available pincer NHC precursors, CoCl2, and a base enabled highly efficient hydrogenation of a broad range of ketones and aldehydes (over 50 examples and up to a turnover number [TON] of 2,610). Diastereodivergent hydrogenation of substituted cyclohexanone derivatives was also realized in high selectivities. Moreover, the preparation of a well-defined bis(NHCs)-Co complex via this pincer NHC ligand consisting of a N-H substructure was successful, and it exhibits equally excellent catalytic activity for the hydrogenation of C=O bonds.
- Zhong, Rui,Wei, Zeyuan,Zhang, Wei,Liu, Shun,Liu, Qiang
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supporting information
p. 1552 - 1566
(2019/06/14)
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- The open d-shell enforces the active space in 3d metal catalysis: Highly enantioselective chromium(ii) pincer catalysed hydrosilylation of ketones
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Bis(oxazolinyldimethylmethyl)pyrrol (PdmBox) stereodirecting ligands provided the key to the chromium(ii)-catalysed highly enantioselective hydrosilylation of ketones. A rare square planar, chiral chromium(ii) alkyl complex was found to serve as a potent precatalyst for the reduction of a broad range of aryl alkyl and dialkyl ketone derivatives. The stereoelectronic preference of the open d4 shell of chromium(ii) firmly locks the molecular catalyst in a square planar geometry giving rise to two blocked quadrants of the coordination sphere. This earth-abundant base metal catalytic platform produces the corresponding chiral alcohols in excellent isolated yields with up to 98 %ee under mild reaction conditions (-40 °C to rt) and at low catalyst loadings (as low as 0.5 mol%).
- Schiwek, Christian H.,Vasilenko, Vladislav,Wadepohl, Hubert,Gade, Lutz H.
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supporting information
p. 9139 - 9142
(2018/08/24)
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- Improving Catalytic Hydrogenation Performance of Pd Nanoparticles by Electronic Modulation Using Phosphine Ligands
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Tuning the activity and selectivity of metal nanoparticles (NPs) is a long-term pursuit in the field of catalysis. Herein, we report successfully improving both the activity and chemoselectivity of Pd NPs (1.1 nm) with triphenylphosphine (PPh3) cross-linked in the nanopore of FDU-12. The electron-donating effect of PPh3 increases the surface electronic density of Pd NPs and weakens the Pd-H bond, as evidenced by the results of XPS, in situ FT-IR adsorption of CO, and H2-D2 exchange reactions. Consequently, Pd NPs modified with PPh3 obtain >99% selectivity to 1-phenylethanol in acetophenone hydrogenation and 94% selectivity to styrene in phenylacetylene hydrogenation. Furthermore, the activity of Pd NPs is enhanced and suppressed by PPh3, respectively, in the hydrogenation of electrophilic nitro compounds and nucleophilic carbonyl substrates. Our primary results shed some light on judiciously choosing organic ligands for modifying the catalytic performance of metal NPs toward specific chemical transformations.
- Guo, Miao,Li, He,Ren, Yiqi,Ren, Xiaomin,Yang, Qihua,Li, Can
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p. 6476 - 6485
(2018/06/18)
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- Homogeneous Palladium-Catalyzed Transfer Hydrogenolysis of Benzylic Alcohols Using Formic Acid as Reductant
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We report the first homogeneous palladium-based transfer hydrogenolysis of benzylic alcohols using an in situ formed palladium-phosphine complex and formic acid as reducing agent. The reaction requires a catalyst loading as low as only 1 mol % of palladium and just a slight excess of reductant to obtain the deoxygenated alkylarenes in good to excellent yields. Besides demonstrating the broad applicability for primary, secondary and tertiary benzylic alcohols, a reaction intermediate could be identified. Additionally, it could be shown that partial oxidation of the applied phosphine ligand was beneficial for the course of the reaction, presumably by stabilizing the active catalyst. Reaction profiles and catalyst poisoning experiments were used to characterize the catalyst, the results of which indicate a homogeneous metal complex as the active species.
- Ciszek, Benjamin,Fleischer, Ivana
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supporting information
p. 12259 - 12263
(2018/08/28)
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- P450 BM3-Catalyzed Regio- and Stereoselective Hydroxylation Aiming at the Synthesis of Phthalides and Isocoumarins
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Cytochrome P450 BM3 monooxygenases are able to catalyze the regio- and stereoselective oxygenation of a broad range of substrates, with promising potential for synthetic applications. To study the suitability of P450 BM3 variants for stereoselective benzylic hydroxylation of 2-alkylated benzoic acid esters, the biotransformation of methyl 2-ethylbenzoate, resulting in both enantiomeric forms of 3-methylphthalide, was investigated. In the case of methyl 2-propylbenzoate as a substrate the regioselectivity of the reaction was shifted towards β-hydroxylation, resulting in the synthesis of enantioenriched R- and S-configured 3-methylisochroman-1-one. The potential of P450 BM3 variants for regio- and stereoselective synthesis of phthalides and isocoumarins offers a new route to a class of compounds that are valuable synthons for a variety of natural compounds.
- Holec, Claudia,Hartrampf, Ute,Neufeld, Katharina,Pietruszka, J?rg
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p. 676 - 684
(2017/04/11)
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- Chirality dihydrogen silane compound and synthetic method and application thereof
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The invention discloses a chirality dihydrogen silane compound. The chirality dihydrogen silane compound is as shown in the formula IV. In the formula IV, X represents a chiral carbon atom. The invention further discloses a synthetic method for the chirality dihydrogen silane compound. The method comprises the following steps: using olefin shown in the formula I and silane shown in the formula II as raw materials, and using a chiral CoX2-OIP complex compound as a catalyst, in the existence of a reducing agent, reacting to obtain the chirality dihydrogen silane compound shown in the formula IV. The synthetic method is suitable for different types of the olefins, the reaction condition is moderate, the operation is simple and convenient, and the atomic economy is high. The reaction does not need to be added with any other toxic transition metal ions, the reaction yield is better and is 53%-97% generally, and the enantio-selectivity is higher and is 81%-99% and gt generally. The provided chirality dihydrogen silane compound shown in the formula IV can be used for synthesizing a chiral alcohol compound, a chiral silicon alcohol compound, a chiral polysubstituted silane compound and so on.
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Paragraph 0208; 0209; 0210; 0211; 0212; 0213; 0214
(2017/10/22)
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- Mechanism-Based Enantiodivergence in Manganese Reduction Catalysis: A Chiral Pincer Complex for the Highly Enantioselective Hydroboration of Ketones
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A manganese alkyl complex containing a chiral bis(oxazolinyl-methylidene)isoindoline pincer ligand is a precatalyst for a catalytic system of unprecedented activity and selectivity in the enantioselective hydroboration of ketones, thus producing preparatively useful chiral alcohols in excellent yields with up to greater than 99 % ee. It is applicable for both aryl alkyl and dialkyl ketone reduction under mild reaction conditions (TOF >450 h?1 at ?40 °C). The earth-abundant base-metal catalyst operates at very low catalyst loadings (as low as 0.1 mol %) and with a high level of functional-group tolerance. There is evidence for the existence of two distinct mechanistic pathways for manganese-catalyzed hydride transfer and their role for enantiocontrol in the selectivity-determining step is presented.
- Vasilenko, Vladislav,Blasius, Clemens K.,Wadepohl, Hubert,Gade, Lutz H.
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supporting information
p. 8393 - 8397
(2017/07/11)
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- CGRP RECEPTOR ANTAGONISTS
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The present invention provides a compound of Formula II: (II) or a pharmaceutically acceptable salt thereof.
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Page/Page column 45; 46
(2017/03/25)
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- TETRAHYDROQUINOLINE SUBSTITUTED HYDROXAMIC ACIDS AS SELECTIVE HISTONE DEACETYLASE 6 INHIBITORS
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Histone deacetylases inhibitors (HDACIs) and compositions containing the same are disclosed. Methods of treating diseases and conditions wherein inhibition of HDAC provides a benefit, like a cancer, a neurodegenerative disorder, a neurological disease, tr
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Paragraph 0179-0180
(2017/09/08)
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- Iminophenyl Oxazolinylphenylamine for Enantioselective Cobalt-Catalyzed Hydrosilylation of Aryl Ketones
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A new family of chiral iminophenyl oxazolinylphenylamines (IPOPA) was designed and synthesized through three steps from commercially available starting materials. An efficient cobalt-catalyzed asymmetric hydrosilylation of simple ketones with a low catalyst loading of CoCl2 and IPOPA was developed to afford chiral alcohols in good yields with high enantioselectivities.
- Chen, Xu,Lu, Zhan
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supporting information
p. 4658 - 4661
(2016/09/28)
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- The Asymmetric Piers Hydrosilylation
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An axially chiral, cyclic borane decorated with just one C6F5 group at the boron atom promotes the highly enantioselective hydrosilylation of acetophenone derivatives without assistance of an additional Lewis base (up to 99% ee). The reaction is an unprecedented asymmetric variant of Piers' B(C6F5)3-catalyzed carbonyl hydrosilylation. The steric congestion imparted by the 3,3′-disubstituted binaphthyl backbone of the borane catalyst as well as the use of reactive trihydrosilanes as reducing agents are keys to success.
- Süsse, Lars,Hermeke, Julia,Oestreich, Martin
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supporting information
p. 6940 - 6943
(2016/07/06)
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- Selective Catalytic Hydrogenations of Nitriles, Ketones, and Aldehydes by Well-Defined Manganese Pincer Complexes
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Hydrogenations constitute fundamental processes in organic chemistry and allow for atom-efficient and clean functional group transformations. In fact, the selective reduction of nitriles, ketones, and aldehydes with molecular hydrogen permits access to a green synthesis of valuable amines and alcohols. Despite more than a century of developments in homogeneous and heterogeneous catalysis, efforts toward the creation of new useful and broadly applicable catalyst systems are ongoing. Recently, Earth-abundant metals have attracted significant interest in this area. In the present study, we describe for the first time specific molecular-defined manganese complexes that allow for the hydrogenation of various polar functional groups. Under optimal conditions, we achieve good functional group tolerance, and industrially important substrates, e.g., for the flavor and fragrance industry, are selectively reduced.
- Elangovan, Saravanakumar,Topf, Christoph,Fischer, Steffen,Jiao, Haijun,Spannenberg, Anke,Baumann, Wolfgang,Ludwig, Ralf,Junge, Kathrin,Beller, Matthias
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supporting information
p. 8809 - 8814
(2016/07/29)
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- Highly Active and Selective Manganese C=O Bond Hydrogenation Catalysts: The Importance of the Multidentate Ligand, the Ancillary Ligands, and the Oxidation State
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The replacement of expensive noble metals by earth-abundant transition metals is a central topic in catalysis. Herein, we introduce a highly active and selective homogeneous manganese-based C=O bond hydrogenation catalyst. Our catalyst has a broad substrate scope, it is able to hydrogenate aryl–alkyl, diaryl, dialkyl, and cycloalkyl ketones as well as aldehydes. A very good functional group tolerance including the quantitative and selective hydrogenation of a ketone in the presence of a non-shielded olefin is observed. In Mn hydrogenation catalysis, the combination of the multidentate ligand, the oxidation state of the metal, and the choice of the right ancillary ligand is crucial for high activity. This observation emphasizes an advantage and the importance of homogeneous catalysts in 3d-metal catalysis. For coordination compounds, fine-tuning of a complex coordination environment is easily accomplished in comparison to enzyme and/or heterogeneous catalysts.
- Kallmeier, Fabian,Irrgang, Torsten,Dietel, Thomas,Kempe, Rhett
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supporting information
p. 11806 - 11809
(2016/11/16)
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- Indazole derivative, composition and uses thereof
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The present invention discloses an indazole derivative represented by a formula (I) and used for treating type 2 diabetes mellitus or a pharmaceutically acceptable salt, a solvate, a metabolite, a polymorph, a tautomer or a prodrug thereof. The present invention further discloses a pharmaceutical composition containing the substance, applications of the composition in preparation of drugs, and a method for treating type II diabetes mellitus. The formula (I) is defined in the specification.
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Paragraph 0134; 0135
(2017/01/02)
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- Cobalt-catalyzed asymmetric hydroboration of aryl ketones with pinacolborane
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The highly enantioselective cobalt-catalyzed hydroboration reaction of aryl ketones with HBpin was developed using iminopyridine oxazoline ligands. Halides, amines, ethers, sulfides, esters and amides are well tolerated under the mild reaction conditions, demonstrating its synthetic advantage. Substituted diaryl ketones could also be hydroborated with high enantioselectivity.
- Guo, Jun,Chen, Jianhui,Lu, Zhan
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supporting information
p. 5725 - 5727
(2015/03/30)
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- Modulators of methyl modifying enzymes, compositions and uses thereof
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Agents for modulating methyl modifying enzymes, compositions and uses thereof are provided herein.
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Page/Page column 132; 133; 200; 201
(2015/12/26)
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- Iron achieves noble metal reactivity and selectivity: Highly reactive and enantioselective iron complexes as catalysts in the hydrosilylation of ketones
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Chiral iron alkyl and iron alkoxide complexes bearing boxmi pincers as stereodirecting ligands have been employed as catalysts for enantioselective hydrosilylation reactions with unprecedented activity and selectivity (TOF = 240 h-1 at -40 °C, ee up to 99% for alkyl aryl ketones), which match the performance of previously established noble-metal-based catalysts. This shows the potential of earth-abundant metals such as iron for replacing platinum-metals without any drawbacks for the reaction design.
- Bleith, Tim,Wadepohl, Hubert,Gade, Lutz H.
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supporting information
p. 2456 - 2459
(2015/03/04)
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- Ruthenium-catalyzed oxidative kinetic resolution of unactivated and activated secondary alcohols with air as the hydrogen acceptor at room temperature
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Enantiopure alcohols are versatile building blocks for asymmetric synthesis and the kinetic resolution (KR) of racemic alcohols is a reliable method for preparing them. Although many KR methods have been developed, oxidative kinetic resolution (OKR), in which dioxygen is used as the hydrogen acceptor, is the most atom-efficient. Dioxygen is ubiquitous in air, which is abundant and safe to handle. Therefore, OKR with air has been intensively investigated and the OKR of benzylic alcohols was recently achieved by using an Ir catalyst without any adjuvant. However, the OKR of unactivated alcohols remains a challenge. An [(aqua)Ru(salen)] catalyzed OKR with air as the hydrogen acceptor was developed, in which the aqua ligand is exchanged with alcohol and the Ru complex undergoes single electron transfer to dioxygen and subsequent alcohol oxidation. This OKR can be applied without any adjuvant to activated and unactivated alcohols with good to high enantioselectivity. The unique influence of substrate inhibition on the enantioselectivity of the OKR is also described. Alcohol resolution: An (aqua)ruthenium salen complex catalyzes the efficient oxidative kinetic resolution of both activated and unactivated secondary alcohols with air as the hydrogen acceptor at room temperature. The reaction is compatible with various functional groups, including halogen, ether, silyl ether, and ester groups. The reaction rate is lower at higher substrate concentrations as a result of substrate inhibition.
- Mizoguchi, Hirotaka,Uchida, Tatsuya,Katsuki, Tsutomu
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supporting information
p. 3178 - 3182
(2014/04/03)
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- Formal hydration of non-activated terminal olefins using tandem catalysts
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The hydration of terminal olefins to secondary alcohols has been achieved using a Pd(ii)/Ru(ii) catalyst combination with high regioselectivity and yields. Both vinyl arenes and aliphatic olefins can be hydrated easily with the tandem catalyst system using a low catalyst loading of 1 mol%. The Royal Society of Chemistry 2014.
- Yang, Yongsheng,Guo, Jiayi,Ng, Huimin,Chen, Zhiyong,Teo, Peili
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supporting information
p. 2608 - 2611
(2014/03/21)
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- Commutative reduction of aromatic ketones to arylmethylenes/alcohols by hypophosphites catalyzed by Pd/C under biphasic conditions
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An efficient method is reported to reduce aromatic ketones selectively into arylmethylenes or alcohols with hypophosphites and Pd/C, depending on the selected conditions. This study could represent a promising alternative to the classical uses of standard hydrides or molecular hydrogen involved in reduction and deoxygenation procedures.
- Guyon, Carole,Baron, Marc,Lemaire, Marc,Popowycz, Florence,Métay, Estelle
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supporting information
p. 2088 - 2095
(2014/03/21)
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- Selective transfer hydrogenation and hydrogenation of ketones using a defined monofunctional (P^N(Bn)^N(Bn)^P)-RuII complex
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A defined (P^N^N^P)-Ru complex possessing tertiary amines within the ligand backbone proved to be highly active both in transfer hydrogenations and hydrogenations of a variety of ketones. As compared to the existing catalytic systems, no bifunctional activation of H2 or of the substrate by the metal center and a secondary amine within the ligand backbone is required to obtain high activities at catalyst loadings of down to 10 ppm. Monofunctional but good: A defined (P N N P)-Ru complex possessing tertiary amines within the ligand backbone proved to be highly active both in transfer hydrogenations and hydrogenations of a variety of ketones (see scheme).
- Hsu, Shih-Fan,Plietker, Bernd
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supporting information
p. 4242 - 4245
(2014/05/06)
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- Biphasic glycerol/2-MeTHF, ruthenium-catalysed enantioselective transfer hydrogenation of ketones using sodium hypophosphite as hydrogen donor
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Sodium hypophosphite has been used as an efficient hydrogen donor in the transfer hydrogenation of aliphatic and aromatic ketones in the presence of [RuCl2(p-cymene)]2 and 2,2′-bipyridine in water. The corresponding alcohols were isolated in moderate to excellent yields (39-95 %). Good chemoselectivity was observed with ester, nitrile and halide functionalities in the ketones not being reduced. An enantioselective version of the reaction using [RuCl(p-cymene){(R,R)-TsDPEN}] as catalyst in a glycerol/2-MeTHF biphasic solvent mixture has been developed and allowed the reduction of (hetero)aromatic ketones with excellent chemo- and enantioselectivities (up to 97 % ee). Sodium hypophosphite has been used in the reduction of ketones in water (nine examples, 40-95 % yield). An original glycerol/2-MeTHF biphasic solvent system has been developed for the enantioselective version of the reaction. This system allows the preparation of aryl alkyl alcohols with up to 97 % ee (22 examples). Copyright
- Guyon, Carole,Metay, Estelle,Duguet, Nicolas,Lemaire, Marc
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supporting information
p. 5439 - 5444
(2013/09/02)
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- MODULATORS OF METHYL MODIFYING ENZYMES, COMPOSITIONS AND USES THEREOF
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Agents for modulating methyl modifying enzymes, compositions and uses thereof are provided herein
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Paragraph 00243; 00245
(2013/06/05)
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- Palladium-catalyzed hydrogenation with use of ionic liquid bis(2-hydroxyethyl)ammonium formate [BHEA][HCO2] as a solvent and hydrogen source
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We designed ionic liquid bis(2-hydroxyethyl)ammonium formate [BHEA][HCO2] for use as a solvent and hydrogen donor for hydrogenation. Catalytic hydrogenation of aromatic ketones, nitro groups, and olefins with PdCl2 in [BHEA][HCO2] generated the corresponding reduction products. Selective reduction of aromatic ketones over aliphatic ketones was observed. Hydrogenolysis of benzyl ethers and benzyl amines also proceeded. All these reactions were successfully carried out in good to excellent yields under mild and nonflammable conditions. In addition, the ionic liquid and Pd source can be reused several times.
- Suzuki, Hideyuki,Yoshioka, Seiki,Igesaka, Ami,Nishioka, Hiromi,Takeuchi, Yasuo
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p. 6399 - 6403
(2013/07/25)
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- General and highly efficient iron-catalyzed hydrogenation of aldehydes, ketones, and α,β-unsaturated aldehydes
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EnvIRONmentally friendly: The title hydrogenation of aldehydes, ketones, and α,β-unsaturated aldehydes is reported. In the presence of the catalyst 1, primary, secondary, and allylic alcohols were obtained in good to excellent yields under mild reaction conditions. The catalyst is easily and inexpensively prepared, and is also stable to air, water, and column chromatography. Copyright
- Fleischer, Steffen,Zhou, Shaolin,Junge, Kathrin,Beller, Matthias
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p. 5120 - 5124
(2013/06/27)
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